This invention relates to an interlocking chain unit to be incorporated in an interlocking chain type forward and backward actuating device used for example in manufacturing facilities in various manufacturing fields, transportation facilities in the transportation field, nursing care facilities in medical and welfare fields, and stage facilities in art fields.
Japanese Patent Application Publication No. 2012-145168 discloses an interlocking chain type forward and backward actuating device including a base and an actuation target to move relative to the base. FIG. 6 shows an interlocking chain unit 700 of a first mode known as an interlocking chain unit to be incorporated in this device.
As shown in FIG. 6, the interlocking chain unit 700 includes a pair of case plates 720, a first guide plate 730A, a second guide plate 730B, a third guide plate 730C, a first hollow collar 750A, a second hollow collar 750B, a third hollow collar 750C, and a fourth hollow collar 750D. The pair of case plates 720 supports a sprocket shaft 770 such that the sprocket shaft 770 can rotate freely. The pair of case plates 720 forms part of a case for the interlocking chain unit 700. The pair of case plates 720 is configured to cover sprockets SP to transmit power to an interlocking chain not shown in the drawings, and a bifurcation area of each of the first to third guide plates 730A to 730C.
The first to third guide plates 730A to 730C are arranged between a first case plate 720A and a second case plate 720B forming the pair of case plates 720. The first to third guide plates 730A to 730C are configured to guide the interlocking chain, thereby shifting the interlocking chain between a state where the interlocking chain is disengaged and a state where the interlocking chain is interlocked to become rigid.
The first case plate 720A is given a screw hole 723A. The second case plate 720B is given a screw insertion hole 722B. The first, second, and third guide plates 730A, 730B, and 730C are given a passage hole 731A, a passage hole 731B, and a passage hole 731C respectively.
The first hollow collar 750A is arranged between the first case plate 720A and the first guide plate 730A. The second hollow collar 750B is arranged between the first and second guide plates 730A and 730B. Likewise, the third hollow collar 750C is arranged between the second and third guide plates 730B and 730C. The fourth hollow collar 750D is arranged between the third guide plate 730C and the second case plate 720B.
A fixing bolt 760 is threaded from the outside of the second case plate 720B into the screw hole 723A of the first case plate 720A while passing through the screw insertion hole 722B, the fourth hollow collar 750D, the passage hole 731C of the third guide plate 730C, the third hollow collar 750C, the passage hole 731B of the second guide plate 730B, the second hollow collar 750B, the passage hole 731A of the first guide plate 730A, and the first hollow collar 750A.
In this unit, the sprockets SP and the first to third guide plates 730A to 730C should be placed in positions precisely adjusted relative to each other. For this purpose, assembly of the unit proceeds while the positions of the first to third guide plates 730A to 730C are adjusted with respect to the pair of case plates 720. This however extends the time for assembling the unit while making it difficult to assure the precision of the position of each component.
More specifically, a gap between the pair of case plates 720 is determined by the sprocket shaft 770, so that it is susceptible to the thicknesses of the first to third guide plates 730A to 730C or the lengths of the first to fourth hollow collars 750A to 750D. This might cause a loose fit or an excessively tight fit of the fixing bolt 760. In either case, the assembled unit should be disassembled for shim adjustment.
In the aforementioned structure, a position as viewed in a direction perpendicular to a chain width direction T is determined based only on the diameter of the fixing bolt 760 and those of the passage holes 731A to 731C of the first to third guide plates 730A to 730C respectively. This also makes it difficult to sufficiently assure the precision of the positions of the sprockets SP and that of the positions of the first to third guide plates 730A to 730C relative to each other. This might be handled by an interlocking chain unit 800 of a second mode shown in FIG. 7.
As shown in FIG. 7, the interlocking chain unit 800 includes a pair of case plates 820, a first guide plate 830A, a second guide plate 830B, a third guide plate 830C, a first hollow collar 850A, a second hollow collar 850B, and a hollow stepped bar 890. The pair of case plates 820 supports a sprocket shaft 870 such that the sprocket shaft 870 can rotate freely. The pair of case plates 820 forms part of a case for the interlocking chain unit 800. The pair of case plates 820 is configured to cover sprockets SP and a bifurcation area of each the first to third guide plates 830A to 830C.
The pair of case plates 820 is composed of a first case plate 820A and a second case plate 820B. The first case plate 820A does not contact a fixing bolt 860. The first hollow collar 850A is arranged between the first and second guide plates 830A and 830B. The second hollow collar 850B is arranged between the second and third guide plates 830B and 830C.
The hollow stepped bar 890 has a large-diameter part and a small-diameter part smaller in diameter than the large-diameter part. The large-diameter part is arranged between the second case plate 820B and the third guide plate 830C. The small-diameter part passes through a passage hole 831C of the third guide plate 830C, the second hollow collar 850B, a passage hole 831B of the second guide plate 830B, the first hollow collar 850A, and a passage hole 831A of the first guide plate 830A. The fixing bolt 860 passes through the hollow stepped bar 890 from between the first case plate 820A and the first guide plate 830A and is threaded into a screw hole 823B of the second case plate 820B.
In the structure of the second mode, however, the cantilever structure of the fixing bolt 860 cannot assure the strength of the assembled interlocking chain unit 800 sufficiently. Further, a load applied from an interlocking chain might deflect the fixing bolt 860 easily and make guide plate deviate easily relative to a case plate.